The invention has particular, although not exclusive, utility with respect to press brakes and other types of machines having an active member with which an operator works in close proximity to and can have a body member enter the neighbourhood of an active member during traversing of the active member or during traversing of a co-operating member converging with the active member, such as occurs in an upstroking press brake. The invention is a development of the safety apparatus disclosed in Australian Patent Application No. 27084/92, which is incorporated herein by reference.